US Presidents Often Use Their Constitutional Power to Intervene Overseas

As U.S. President Barack Obama weighs whether to attack Syria for its alleged use of chemical weapons against rebels last week, he must consider significant legal factors.

The U.S. Constitution says the president is the commander in chief of the military, but it gives Congress the power to declare war and control war funding. In addition, a four-decade-old U.S. war powers law requires the president to notify Congress within 48 hours of committing to military action and forbids armed forces from remaining for more than 60 days without lawmakers' approval.

Since its enactment, the war powers resolution has been a point of contention between U.S. presidents and Congress. American leaders have several times authorized overseas military intervention after consultation with congressional leaders, but often without getting specific approval with a congressional vote.

Two years ago, President Obama ordered U.S. military participation in bombing Libya to support U.N. resolutions, but did not get congressional approval.

With no immediate U.N. resolution on combating Syria, the United States might have to rely on allies such as Britain and France if it decides to take action.

A senior State Department official says Mr. Obama is "studying the facts and will be making an informed decision about the responsible way forward."

In an interview last week on CNN, the American leader noted that "there are rules of international law" governing warfare.

Mr. Obama said "when you start seeing chemical weapons used on a large scale, ... that starts getting to some core national interests that the United States has, both in terms of us making sure that weapons of mass destruction are not proliferating, as well as needing to protect our allies, our bases in the region."

He said, "... as difficult as the problem is, this is something that is going to require America's attention, hopefully the entire international community's attention."

No decision has been made for U.S. intervention, such as firing missiles from U.S. warships stationed in the eastern Mediterranean at Syrian military targets. Some U.S. lawmakers, including Mr. Obama's opponent in the 2008 presidential election, Senator John McCain, have called for such limited strikes.